Posts
741
Joined
11/19/2010
Location
Soddy Daisy, TN
US
Edited Date/Time
11/13/2017 10:30am
To make a long story short:
I posted back in July showing my sons RMZ250 engine after a piston failure. What I didn't write is that it happen on a big step up, in mid air (of course), and he ended up with a broken pelvis and collarbone. I was kinda tore up over the whole thing (since I do the work on the bikes) and didnt have the attitude to tear it down. So a buddy of mine, whos is an expert moto mechanic and fomer local pro, offered to do it. I pulled the motor, he rebuilt it with a wrench rabbit kit and OEM valves and springs and also had the seats cut. A couple weeks ago he got done (no hurry, since my son is still not cleared to ride) and I put it all back together. He also found have a circlip in the oil strainer so it could have been a circlip that worked it way out and destroyed everything. I know how you need to install the circlip with the opening either up or down. So it could have been my fault. anyway....
I started it and rode it around the yard. It ran like a dog. would not rev worth a crap. Almost felt like the rear brake was on constantly. I then hopped on my bike, (13 RMZ250, identical bike with same gas from the crash and uncleaned air filter from that day of riding) and it ran fine. So I called my buddy, took it over there, he rode it and we all agreed it ran like a dog. Our guess it was 1 tooth off on timing.
He checked timing and it was good. Took off the head and there is a sticky goo on top of the piston. This is essentially a brand new engine that has 2 trips around the yard on it. It almost looks like air filter oil burnt up. Air filter is fine, nothing in the intake, just looks like poor combustion which is making the bike run like crap.
Has anyone else had this problem? Any guesses of what it could be? It has new plug, air filter is fine, gas is fine. When I take off the injector/throttle body I take it off as one piece and replace as one piece. I have no idea what inside there. The bike ran excellent up until castostrophic failure. Any help appreciated.
I posted back in July showing my sons RMZ250 engine after a piston failure. What I didn't write is that it happen on a big step up, in mid air (of course), and he ended up with a broken pelvis and collarbone. I was kinda tore up over the whole thing (since I do the work on the bikes) and didnt have the attitude to tear it down. So a buddy of mine, whos is an expert moto mechanic and fomer local pro, offered to do it. I pulled the motor, he rebuilt it with a wrench rabbit kit and OEM valves and springs and also had the seats cut. A couple weeks ago he got done (no hurry, since my son is still not cleared to ride) and I put it all back together. He also found have a circlip in the oil strainer so it could have been a circlip that worked it way out and destroyed everything. I know how you need to install the circlip with the opening either up or down. So it could have been my fault. anyway....
I started it and rode it around the yard. It ran like a dog. would not rev worth a crap. Almost felt like the rear brake was on constantly. I then hopped on my bike, (13 RMZ250, identical bike with same gas from the crash and uncleaned air filter from that day of riding) and it ran fine. So I called my buddy, took it over there, he rode it and we all agreed it ran like a dog. Our guess it was 1 tooth off on timing.
He checked timing and it was good. Took off the head and there is a sticky goo on top of the piston. This is essentially a brand new engine that has 2 trips around the yard on it. It almost looks like air filter oil burnt up. Air filter is fine, nothing in the intake, just looks like poor combustion which is making the bike run like crap.
Has anyone else had this problem? Any guesses of what it could be? It has new plug, air filter is fine, gas is fine. When I take off the injector/throttle body I take it off as one piece and replace as one piece. I have no idea what inside there. The bike ran excellent up until castostrophic failure. Any help appreciated.
Also, was the cam chain replaced when the rebuild was done? If not they can stretch enough to cause cam timing issues and make the bike run poorly.
Paw Paw
Thanks for the advice
Paw Paw
The Shop
Paw Paw
Paw Paw
Did you ever clean the injector? If dirty it can allow larger than usable droplet size of fuel to enter the combustion chamber and not burn. When that happens you have poor performance and it can create the deposits.
I would clean the injector or replace it before I did any thing else.
Paw Paw
Anyway, finally got 2 good bikes running again and me and my son can go riding. whew
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